Sounds like you are having a paradoxical reaction to the medication. I would stop taking it. That means that you are reacting the opposite way to it than you should. This happens to me with pain meds and sedations meds. They had me on 3600 mg of Neurontin a night. Now, that one worked for sleep, but not for the pain. It gave me horrible migraines. I was so hoping that it would work. When in pain we are pretty much willing to try anything.
At least they started you out on a low dose.
Anti-depressants are a new way to treat pain patients. It doesn't so much cure the pain but helps you live with the pain. I can't take those either as they make me psychotic and I can't eat on them. But, they work for a lot of people. It takes up to four weeks to reap any benefits, though, so it is a roll of the dice to see if they work for people.
I had the reaction that you are having when I took Bextra. It intensified everything. I had the same symptoms that I was trying to cure, only worse. When I quit the Bextra, the back quit hurting. I still have the SI problem, but not a back problem. I was taking it for the arthritis, but it only made it worse. Good thing that I quit because now they say that it is right up there with Vioxx with potentional deadly side effects.
If it were me, I would stop the med.